The emergence of new ceramic tools is the first new technological achievement for mankind to reform mechanical cutting by using ceramic materials. As early as the beginning of the 20th century, Germany and the United Kingdom had begun to seek to replace traditional carbon steel tools with ceramic tools. Ceramic materials have become a new generation of tool materials due to their high hardness and high temperature resistance. However, ceramics are also limited by their well-known brittleness. Therefore, how to overcome the brittleness of ceramic tool materials and improve its toughness has become a ceramic for nearly a hundred years. The main subject of tool research. The range of applications for ceramics is also growing.
The main reasons for the engineering technology industry to develop and promote ceramic knives are (1) to greatly improve production efficiency; and (2) to be determined by the depletion of tungsten resources, the main component of high-speed steel and cemented carbide, on a global scale. It was estimated in the early 1990s that the world's proven tungsten resources were only used for 50 years. Tungsten is the most scarce resource in the world, but its consumption in cutting tool materials is very large, which leads to the rising price of tungsten ore, which has risen many times in several decades. This has also promoted the development of ceramic tools to a certain extent. Promotion, the development of ceramic tool materials has achieved remarkable results.
So far, the materials used as ceramic knives have formed alumina ceramics, alumina-metal ceramics, alumina-carbide ceramics, alumina-carbide cermets, alumina-nitride cermets and the latest research success. Boron nitride ceramics, and silicon nitride ceramic tools and other materials. As far as the world is concerned, German ceramic tools have not only been used in ordinary machine tools, but have been used as an efficient, stable and reliable tool for digital control machine tool processing and automated production lines; Japanese ceramic blades are in terms of product type, output and quality. With international advanced level; the United States has always been a world leader in the development of oxide-carbide-nitride ceramic tools. Many achievements have been made in the development and application of Chinese ceramic tools.
1. Alumina ceramic cutter: Pure Al2O3 is used in the material. The additive is beneficial to strengthen the flexural strength of Al2O3, but the high temperature performance is reduced, so it is better to use pure alumina ceramic material.
Al2O3 ceramics have higher room temperature hardness and high temperature hardness than cemented carbide materials. Although the flexural strength of Al2O3 ceramics is low at room temperature, its flexural strength decreases less as the temperature rises during use. It is quite suitable for high speed cutting based on this characteristic. Al2O3 ceramics have good compressive strength at room temperature and high temperature, and can overcome the disadvantages of deformation and collapse of the high-speed steel cutter and carbide cutting blade. In addition, Al2O3 ceramics can be used in physical thermal properties and resistance to oxidation, adhesion and chemical inertness. However, alumina ceramic cutters are more prone to bond wear and notch wear when cutting iron alloys and steel parts. As the longest used tool material, alumina ceramic tools are ideal for cutting hard and brittle metal materials such as chilled cast iron or hardened steel at high speeds; for cutting large parts and for cutting high precision parts. machining. Alumina ceramic cutters are inferior in short-cutting, small-part, intermittent cutting of steel and single-material materials such as Mg, Al, Ti and Be, and their alloy materials. It is easy to cause diffusion wear or spalling and chipping of the tool. Such defects are the ointment.
2. Alumina-metal ceramics: In order to improve the toughness of Al2O3 ceramic tools, less than 10% of metal elements such as Cr, CO, MO, W, Ti, Fe are introduced into the material, thereby forming Al2O3 cermet, so that the material density and resistance Strong bending strength and hardness are improved. However, due to the low creep strength of the alumina-cermet tool, the oxidation resistance is poor, and the promotion is not good.
3. Alumina-carbide ceramics: A certain proportion of carbides, such as MO2C, WC, TiC, TaC, NbC and Cr3C2, are added to the Al2O3 ceramics to improve the performance of the Al2O3 ceramic tool. When the TiC content is 30%, the durability of the ceramic tool is significantly improved, and the depth of the thermal crack is also small. At present, the international production of hot-pressed Al2O3-TiC ceramic tools adopts this formula. The bending strength and thermal shock resistance of Al2O3—TiC ceramics are better than those of Al2O3 ceramic tools.
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Microscope Slides And Cover Slips
1. The glass slide is used to put the sample to be tested, and the cover glass is covered on the sample to be tested.
2. The glass slide is at the bottom, which is the carrier for the material you want to observe, that is, you want to put something on it.
3. The cover glass is smaller than the slide glass. The glass slide is mainly used to hold the observation objects. The cover glass is covered on the slide glass and used for fixing.
4. The glass slide is a thicker piece of glass in the transfer slide, which is used to carry the real object. The cover fragment is the small round or square thin one.
5. Mounting is a general term for a set of things, including slides, coverslips and loaded objects
6. The cover glass is square, the slide glass is rectangular, and the width is longer than the side of the cover glass.
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